Component structure, power module and power module assembly structure

ABSTRACT

The present disclosure relates to a component structure, a power module and a power module assembly structure having the component structure. The component structure comprises: a first bus bar, having one end extending to a first plane to form a first connecting terminal; a second bus bar, comprising a front portion of the second bus bar and a rear portion of the second bus bar, wherein the front portion of the second bus bar is laminated in parallel with the first bus bar, and the rear portion of the second bus bar is extended to a second plane to form a second connecting terminal; and an external circuit comprising a third bus bar, wherein the third bus bar is settled in parallel with the rear portion of the second bus bar, to reduce a parasitic inductance between the first connecting terminal and the second connecting terminal.

CROSS REFERENCE

The present application is divisional application of U.S. applicationSer. No. 16/003,234, which claims the priority of Chinese PatentApplication No. 201710772709.7, filed on Aug. 31, 2.017, and ChinesePatent Application No. 2.01810010312.9, filed on Jan. 5, 2018, and theentire contents thereof are incorporated herein by reference as part ofthe present application.

TECHNICAL FIELD

The present disclosure relates to the field of power electronicstechnology, and in particular, to a. component structure for connectinga power module and an external circuit, a. power module and a powermodule assembly structure having the component structure.

BACKGROUND

Modem power electronic devices, as an important part of powerconversions, are widely used in the electric power, electronics, motordrivers, and energy industries, it is always an important pursuing goalfor those skilled in the art to ensure long-term stable operation of thepower electronic devices and improve the power conversion efficiency ofthe power electronic devices.

It should be noted that, information disclosed in the above backgroundportion is provided only for better understanding of the background ofthe present disclosure, and thus it may contain information that doesnot form the prior art known by those ordinary skilled in the

SUMMARY

According to one aspect of the present disclosure, there is provided acomponent structure, for connecting a power module and an externalcircuit, wherein the component structure includes:

a first bus bar, having one end extending to a first plane to form afirst connecting terminal;

a second bus bar, including a front portion of the second bus bar and arear portion of the second bus bar, wherein the front portion of thesecond bus bar is laminated in parallel with the first bus bar, and therear portion of the second bus bar is extended to a second plane to forma second connecting terminal; and

the external circuit including a third bus bar, wherein the third busbar is settled in parallel with the rear portion of the second bus bar,to reduce a parasitic inductance between the first connecting terminaland the second connecting terminal.

According to an aspect of the present disclosure, there is provided apower module, wherein the power module includes:

a substrate;

a power unit, disposed on the substrate; and

any one of the component structures described above, the componentstructure connecting the power unit and an external circuit.

According to an aspect of the present disclosure, there is provided apower module assembly structure, wherein the power module assemblystructure includes:

a substrate;

two power elements connected in series, disposed on the substrate; and

a first conductive strip and a second conductive strip, coupled to thetwo power elements respectively, wherein the first conductive strip andthe second conductive strip extend from the substrate to a first side ofthe power module assembly structure in parallel and two connectingterminals are formed on the first side; an extending portion existsbetween the two connecting terminals, and the extending portion overlapswith an external conductive strip to reduce a parasitic inductancebetween the two connecting terminals.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings herein are incorporated in and constitute apart of this specification, illustrate embodiments consistent with thepresent disclosure, and together with the description serve to explainthe principles of the present disclosure. Obviously, the drawings in thefollowing description are merely sonic embodiments of the presentdisclosure, and those skilled in the art can also obtain other drawingsbased on these drawings without any creative work.

FIG. 1 is a schematic diagram of a half-bridge power circuit withcapacitor clamping;

FIG. 2 is a schematic diagram of a half-bridge circuit;

FIG. 3 is a schematic structural view of a laminated bus bar used in thehalf-bridge circuit as shown in FIG. 2;

FIG. 4 is a schematic diagram of a component structure in an exemplaryembodiment of the present disclosure;

FIG. 5 is a schematic diagram of a component structure in an exemplaryembodiment of the present disclosure;

FIG. 6 is a schematic diagram of a component structure in an exemplaryembodiment of the present disclosure;

FIG. 7 is a schematic diagram of a component structure in an exemplaryembodiment of the present disclosure;

FIG. 8 is a schematic diagram of a half-bridge power circuit with diodeclamping;

FIG. 9 is a schematic diagram of a half-bridge power circuit with activeclamping;

FIG. 10 is a schematic diagram of a manner of mounting elements of thecomponent structure in an exemplary embodiment of the presentdisclosure;

FIG. 11 is a schematic diagram of a manner of mounting elements of thecomponent structure in an exemplary embodiment of the presentdisclosure;

FIG. 12 is a schematic diagram of a manner of mounting elements of thecomponent structure in an exemplary embodiment of the presentdisclosure;

FIG. 13 is a schematic diagram of a component structure in an exemplaryembodiment of the present disclosure;

FIG. 14 is a schematic diagram of a component structure in an exemplaryembodiment of the present disclosure;

FIG. 15 is a schematic diagram of a three-level circuit with a clampingcircuit;

FIG. 16 is a schematic diagram of a T-type three-level power circuitwith a snubber capacitor;

FIG. 17 is a schematic sectional view of a power module in an exemplaryembodiment of the present disclosure; and

FIG. 18 is a schematic internal plan view of a power module in anexemplary embodiment of the present disclosure.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings. However, example embodiments can beimplemented in various forms and should not be construed as limited tothe examples set forth herein; rather, these embodiments are provided sothat the present disclosure will be more comprehensive and complete, andwill fully convey the concept of the example embodiments to thoseskilled in the art. The features, structures, or characteristicsdescribed may be combined in any suitable manner in one or moreembodiments.

In addition, the drawings are merely schematic illustrations of thepresent disclosure and are not necessarily drawn to scale. The samereference numerals in the drawings denote the same or similar parts, andthus their repeated description will be omitted,

Power semiconductor elements are core parts of modern power electronicdevices, performance of which directly determines the reliability andpower conversion efficiency of the power electronic devices. In order todesign a more reliable and safer power electronic device with higherperformance, it is desirable that the power semiconductor element hascharacteristics of low voltage stress and low power loss. Powersemiconductor elements used in the power electronic devices operate in aswitching state, and high-frequency switching actions will cause a highcurrent change rate di/dt in the circuit. According to the principle ofthe circuit, a voltage Vs will be generated when a changing current actson a parasitic inductor L_(stray), the calculation formula is asfollows:

V_(s) =L _(stray) di/dt

It can be seen that reducing the parasitic inductance may reduce thegenerated voltage spike when the current change rate is constant. On theother hand, the parasitic inductance is related to the packaging andconnection of the power semiconductor element.

Therefore, in order to reduce the voltage stress across the powersemiconductor device, a circuit for controlling the voltage spike isgenerally placed outside the power semiconductor device and near theconnection terminals. As shown in FIG. 1, it is a schematic diagram of apower semiconductor circuit with a capacitor clamping circuit. Thecapacitor C is usually provided on an external circuit connected to thepower module nearby, such as a laminated bus bar, a PCB system board, acontrol board, and the like. Since the circuits in the periphery of thepower module are usually quite easy to set wiring layers withsuperimposing upper and lower layers, the loop inductance of theperiphery circuit may be controlled at a quite low level, which resultsin that the entire loop inductance is dominated inside the power module.That is, this method may reduce the voltage spike caused by theparasitic inductance outside the power module, but cannot reduce thevoltage spike caused by the parasitic inductance inside the powermodule.

In order to reduce the parasitic inductance inside the power module, alaminated bus bar structure is used inside the power module. Taking anMOSFET half-bridge circuit as an example, FIG. 2 is a schematic diagramof the half-bridge circuit. FIG. 3 is a schematic structural view of alaminated bus bar used in the half-bridge circuit of FIG. 2. As shown inFIG. 3, upper and lower layers of bus bars 310 and 320, in the dashedbox A, the currents of which are with opposite directions superimposewith each other, and the loop inductance inside the power module may bereduced well. However, in the dashed box B, the two bus bars 310 and 320are separated to fan-out terminals 315 and 325 respectively. Due tofactors such as voltage isolation, a distance d of the fan-out portionsbetween the terminals 315 and 325 is relatively far, and the loopinductance between the two fan-out portions is large. That is, thesolution in FIG. 3 does not reduce the parasitic inductance inside thepower module to an ideal value.

Accordingly, in order to reduce the loop inductance, a laminated bus barhas been adopted inside the power module to lead out electrodes.However, due to the separation of the fan-out portions of the bus bar,it is still unable to reduce the parasitic inductance to the optimalvalue. Currently, the parasitic inductance of the external circuitconnected to the power module has been controlled to the minimum. Itseems to have reached a bottleneck stage to achieve an even lowerparasitic inductance by improving the power module and the externalcircuit respectively. In order to solve the above bottleneck problem,the present disclosure proposes a novel component structure which mayconveniently and effectively reduce the loop inductance.

The present disclosure provides a component structure, for connecting apower module and an external circuit. The component structure includes afirst bus bar and a second bus bar. The first bus bar has one endextending to a first plane and a first connecting terminal is formed.The second bus bar includes a front portion of the second bus bar and arear portion of the second bus bar. The front portion of the second busbar is laminated in parallel with the first bus bar, and the rearportion of the second bus bar extends to a second plane and a secondconnecting terminal is formed. The external circuit includes a third busbar. The third bus bar is settled in parallel with the rear portion ofthe second bus bar, to reduce a parasitic inductance between the firstconnecting terminal and the second connecting terminal.

As for a component structure of the present disclosure, within the powermodule, the first bus bar and the front portion of the second bus barare laminated in parallel to form a laminated bus bar, which reduces theparasitic inductance inside the power module. At the fan-out terminalsof the modules, the rear portion of the second bus bar and the third busbar of the external circuit are settled in parallel to form a stackedbus bar structure, which reduces the parasitic inductance between thefan-out terminals of the power module. Through the design of thelaminated bus bars inside the power module and the cooperation of thefan-out terminals inside the power module and the external circuit, theparasitic inductance of the power module is greatly reduced, therebyfacilitating and effectively reducing the voltage stress and power lossof the power electronic semiconductor device, and then improving thereliability and safety of the power electronic devices.

In order to ensure a good parasitic inductance reduction effect, in anexemplary embodiment of the present disclosure, a portion of the thirdbus bar settled in parallel with the rear portion of the second bus baris defined as a front portion of the third bus bar. Surfaces of the rearportion of the second bus bar and the front portion of the third bus bardisposed oppositely are a first surface and a second surfacerespectively. An area ratio of an overlapping area of the rear portionof the second bus bar and the front portion of the third bus bar to thefirst surface is greater than 0.5, and an area ratio of an overlappingarea of the rear portion of the second bus bar and the front portion ofthe third bus bar to the second surface is greater than 0.5. Theinventors have found that when the area ratio of the overlapping area tothe first surface and the area ratio of the overlapping area to thesecond surface are both greater than 0.5, the parasitic inductance canbe effectively reduced. In this embodiment, the area ratio of theoverlapping area to the first surface and the area ratio of theoverlapping area to the second surface may be different.

In order to further ensure a good parasitic inductance reduction effect,in another exemplary embodiment of the present disclosure, the arearatios of the overlapping area of the rear portion of the second bus barand the front portion of the third bus bar to the first surface and thesecond surface are both 1.

In the following, various parts of the component structure of thepresent disclosure will be described in more detail with reference toFIGS. 4 to 13.

FIG. 4 is a schematic diagram of a component structure in an exemplaryembodiment of the present disclosure. The component structure 400 isused for connecting the power module and the external circuit. Thecomponent structure 400 includes a first bus bar 410 and a second busbar 420. In the embodiment, the power module may be a powersemiconductor element, such as an MOS transistor, an IGBT (InsulatedGate Bipolar Transistor), a transistor. Or the power module may be aconversion circuit composed of these power semiconductor elements, forexample, the half-bridge power circuit in FIG. 2. The external circuitmay be an external circuit distribution unit corresponding to the powerdistribution of the power module, but it is not limited thereto.

Continuing to refer to FIG. 4, one end of the first bus bar 410 extendsto a first plane A and a first connecting terminal 415 is formed. Thesecond bus bar 420 includes a front portion of the second bus bar 421and a rear portion of the second bus bar 422. The front portion of thesecond bus bar 421 and the rear portion of the second bus bar 422 areconnected. The front portion of the second bus bar 421 is laminated inparallel with the first bus bar 410, and the rear portion of the secondbus bar extends to a second plane B and a second connecting terminal 425is formed. The first connecting terminal 415 and the second connectingterminal 425 are served as connecting ports between the power module andthe external circuit. The external circuit includes a third bus bar 430.The third bus bar 430 is settled in parallel with the rear portion ofthe second bus bar 422, to reduce a parasitic inductance between thefirst connecting terminal 415 and the second connecting terminal 425. Itshould be noted that only the partial structure of the third bus bar isshown in the figure, and the third bus bar may have a larger area andlength to connect other elements of the external circuit. Since thesubsequent structures are weakly related to the present disclosure, theyare not shown in detail,

A portion of the third bus bar 430 disposed opposite to the rear portionof the second bus bar 422 is further defined as a front portion of thethird bus bar, Surfaces of the rear portion of the second bus bar 422and the front portion of the third bus bar disposed oppositely are afirst surface and a second surface respectively. An area ratio of anoverlapping area of the rear portion of the second bus bar and the frontportion of the third bus bar to the first surface is greater than 0.5,and an area ratio of an overlapping area of the rear portion of thesecond bus bar and the front portion of the third bus bar to the secondsurface is greater than 0.5. In this embodiment, the area ratio of theoverlapping area to the first surface and the area ratio of theoverlapping area to the second surface may be different. In order tofurther ensure a good parasitic inductance reduction effect, the arearatios of the overlapping area of the rear portion of the second bus barand the front portion of the third bus bar to the first surface and thesecond surface may both be 1, which may further effectively reduce theparasitic inductance. That is, the rear portion of the second bus bar422 and the front portion of the third bus bar are overlapped inparallel, and surface areas of the oppositely disposed surfaces areequal.

As shown in FIG. 4, in the present exemplary embodiment, one end of thethird bus bar 430 is provided with a third connecting terminal 435, andthe third connecting terminal 435 is stacked and connected with thefirst connecting terminal 415. For example, the third connectingterminal 435 and the first connecting terminal 415 can be electricallyconnected by mechanical fixing or the like. The external circuit isfurther provided a fourth connecting terminal 445, and the fourthconnecting terminal 445 and the second connecting terminal 425 arestacked and connected. For example, the fourth connecting terminal 445and the second connecting terminal 425 may be electrically connected bymechanical fixing or the like. It should be noted that, another wiringlayer connected with the fourth terminal 445 is arranged in parallelwith the third bus bar, and may have a larger area and length to connectother elements of the external circuit. Since the subsequent structuresare weakly related to the present disclosure, they are not shown indetail.

A schematic diagram of a flow direction of the current in each part ofthe component structure 400 is further shown in FIG. 4. The flowdirection of the current is indicated by the dashed arrow in FIG. 4. Itis assumed that the current flows from the first bus 410 into the powermodule and flows out from the second bus bar 420. As shown in FIG. 4.the current of the external circuit flows to the third connectingterminal 435 via the third bus bar 430. The first connecting terminal415 is connected with the third connecting terminal 435, and the currentflows into the first bus bar 410 through the first connecting terminal415. Then through a circuit distribution design inside the power module,the conversion of the current from the first bus bar 410 to the secondbus bar 420 is achieved, and the current flows out from the second busbar 420. The current flows into the fourth connecting terminal 445through the second connecting terminal 425 and then flows into theexternal circuit. The wiring layer of the external circuit is not shownin detail, and it may usually be implemented by a laminated bus bar, aPCB or a laminated copper bar, but not limited thereto. It should benoted that areas of bus bars of upper and lower layers in FIG. 4 remainstrictly identical, but in fact, because some electrodes need to beconnected to a certain layer of the laminated bus bars, certainavoidance space may need to be left, resulting in that areas of bus barsof upper and lower layers do not have to be strictly consistent. Thoseskilled in the art can determine it flexibly according to needs, and nospecial explanation will be given herein.

In the present exemplary embodiment, the first bus bar 410 and the frontportion of the second bus bar 421 are superimposed, and the interlayerdistance is relatively small. Due to limitations of voltage isolationand material or the like, the thickness of the bus bar is generallybetween 20 μm and 500 μm. Because the direction of the current insidethe first bus bar 410 is opposite to that of the current inside thefront portion of the second bus bar 421, the loop inductance of thisportion is relatively low, which may be usually limited to between 0-9nH. Due to considerations of voltage isolation or the like, a distanceof the rear portion of the second bus bar 422 is relatively long(usually greater than 5 mm), resulting in a large parasitic inductance,which is usually larger than 10 nH. Thus the rear portion of the secondbus bar 422 becomes a major factor affecting the loop inductance.However, in the present exemplary embodiment, since the third bus bar430 of the external circuit and the rear portion of the second bus bar422 are superimposed in parallel or overlapped in parallel with a largeoverlapping area, and the current direction of the third bus bar 430 isopposite to that of the rear portion of the second bus bar 422, the loopinductance can be partially or completely counteracted, so that itsparasitic inductance is greatly reduced. The overall circuit parasiticinductance of the component structure 400 is greatly reduced. Therefore,the present disclosure effectively solves the problem of large circuitinductance through the design of a laminated bus bar inside the powermodule and the cooperation with the bus bar of the external circuit.

From the above, in the present disclosure, a current conductingdirection of the first bus bar 410 is opposite to that of the frontportion of the second bus bar 421, and a current conducting direction ofthe rear portion of the second bus bar 422 is opposite to that of thethird bus bar 450. Since conducting directions of the current areopposite and the counteracting effect of the opposite currents issignificant, the parasitic inductance can be greatly reduced.

Continuing to refer to FIG. 4, the first bus bar 410 further includes afirst extending portion 411 and a first bending portion 412. The firstbending portion 412 is located in the first plane A. The firstconnecting terminal 415 is disposed at an end of the first bendingportion 412. The front portion of the second bus bar 421 furtherincludes a second extending portion 4211 and a second bending portion4212. The first extending portion 411 and the second extending portion4211 are laminated in parallel, and the first bending portion 412 andthe second bending portion 4212 are laminated in parallel. The rearportion of the second bus bar further includes a third extending portion4221 and a third bending portion 4222. The third bending portion 4222 isconnected to the second bending portion 4212, and the third extendingportion 4221 is located in the second plane B. The second connectingterminal 425 is disposed at an end of the third extending portion 4221.In this embodiment, by providing the third bending portion 4222, thefirst plane A and the second plane B can be in the same plane, and theinterlayer distance between the third bus bar 430 and the rear portionof the second bus bar 422 can be minimized, which may further reduce theparasitic inductance.

In the component structure 500 of one exemplary embodiment of thepresent disclosure, as shown in FIG. 5, it may also be the case that thefront portion of the second bus bar 421 includes a second extendingportion 4211 and a second bending portion 4212, the rear portion of thesecond bus bar 422 is connected with the second bending portion 4212,and the second bending portion 4212 and the rear portion of the secondbus bar 422 are both located in the second plane B. That is, the rearportion of the second bus bar 422 does not include the third bendingportion described above. The rear portion of the second bus bar 422 andthe second bending portion 4212 constitute a flat plate structure. Inaddition, in FIG. 5, the third bus bar 430 is adjacent to and disposedunder the rear portion of the second bus bar 422. And the third bus bar430 is connected to the first bus bar 410 through a via hole. In thisway, it may also reduce the interlayer distance between the third busbar 430 and the rear portion of the second bus bar 422, and furtherreduce the parasitic inductance.

It should be noted that only main structures of the component structureare described in FIG. 4 and FIG. 5, in which the insulating layer is notshown, and the thickness, width and the like of the bus bar are alsoschematically depicted instead of being drawn in scale.

Referring to FIG. 6, in one exemplary embodiment of the presentdisclosure, inside the power module, the first bus bar 610 includes afront portion of the first bus bar 611 and a rear portion of the firstbus bar 612. The front portion of the first bus bar 611 and the rearportion of the first bus bar 612 are connected. The rear portion of thefirst bus bar 612 extends to the first plane A and the first connectingterminal 615 is formed. The second bus bar 620 includes a front portionof the second bus bar 621 and a rear portion of the second bus bar 622.The front portion of the second bus bar 621 and the rear portion of thesecond bus bar 622 are connected. The front portion of the second busbar 621 is laminated in parallel with the front portion of the first busbar 611, which may reduce the parasitic inductance inside the powermodule. The rear portion of the second bus bar 622 extends to the secondplane B and the second connecting terminal 625 is formed. As shown inFIG. 6, an extending direction of the rear portion of the first bus bar612 is opposite to that of the rear portion of the second bus bar 622.The first connecting terminal 615 and the second connecting terminal 625may be served as connecting ports between the power module and theexternal circuit. The external circuit further includes a fourth bus bar640 and the third bus bar 630. The third bus bar 630 has a front portionof the third bus bar 631 and a rear portion of the third bus bar 632,and the fourth bus bar 640 has a front portion of the fourth bus bar 641and a rear portion of the fourth bus bar 642. The front portion of thethird bus bar 630 is settled in parallel with the rear portion of thesecond bus bar 622, and the front portion of the third bus bar 631 is aportion of the third bus bar 630 settled in parallel with the rearportion of the second bus bar 622. The front portion of the fourth busbar 641 is settled in parallel with the rear portion of the first busbar 611, and the front portion of the fourth bus bar 641 is a portion ofthe fourth bus bar 640 settled in parallel with the rear portion of thefirst bus bar 612. The laminated structure may reduce the parasiticinductance between the first connecting terminal 615 and the secondconnecting terminal 625. At the same time, the rear portion of thefourth bus bar 642 and the rear portion of the third bus bar 632 arelaminated in para1lel, which further reduces the parasitic inductancebetween the first connecting terminal 615 and the second connectingterminal 625. It should be noted that only the partial structures of thethird bus bar and the fourth bus bar are shown in the figure. and thethird bus bar and the fourth bus bar may have a larger area and lengthto connect other elements of the external circuit. Since thesestructures are weakly related to the present disclosure, they are notshown in detail.

Further, surfaces where the rear portion of the second bus bar 622 andthe front portion of the third bus bar 631 settled in parallel arerespectively a first surface and a second surface. An area ratio of anoverlapping area of the rear portion of the second bus bar 622 and thefront portion of the third bus bar 631 to the first surface is greaterthan 0.5, and an area ratio of an overlapping area of the rear portionof the second bus bar 622 and the front portion of the third bus bar tothe second surface is greater than 0.5. In this embodiment, the arearatio of the overlapping area to the first surface and the area ratio ofthe overlapping area to the second surface may be different. In order tofurther ensure a good parasitic inductance reduction effect, the arearatios of the overlapping area of the rear portion of the second bus barand the front portion of the third bus bar to the first surface and thesecond surface may both be 1, which may further effectively reduce theparasitic inductance. That is, the rear portion of the second bus bar622 and the front portion of the third bus bar 631 are overlapped inparallel, and surface areas of the oppositely disposed surfaces areequal.

Similarly, surfaces of the rear portion of the first bus bar 612 and thefront portion of the fourth bus bar 641 disposed oppositely arerespectively a third surface and a fourth surface. An area ratio of anoverlapping area of the rear portion of the first bus bar 612 and thefront portion of the fourth bus bar 641 to the third surface is greaterthan 0.5, and an area ratio of an overlapping area of the rear portionof the first bus bar 612 and the front portion of the fourth bus bar 641to the fourth surface is greater than 0.5. In this embodiment, the arearatio of the overlapping area to the third surface and the area ratio ofthe overlapping area to the fourth surface may be different. In order tofurther ensure a good parasitic inductance reduction effect, the arearatios of the overlapping area of the rear portion of the first bus barand the front portion of the fourth bus bar to the third surface and thefourth surface may both be 1, which may further effectively reduce theparasitic inductance. That is, the rear portion of the first bus bar 612and the front portion of the fourth bus bar 641 are overlapped inparallel, and surface areas of the surfaces oppositely disposed areequal.

Similarly, surfaces of the rear portion of the fourth bus bar 642 andthe rear portion of the third bus bar 632 disposed oppositely arerespectively a fifth surface and a sixth surface. An area ratio of anoverlapping area of the rear portion of the third bus bar 632 and thefront portion of the fourth bus bar 642 to the fifth surface is greaterthan 0.5, and an area ratio of an overlapping area of the rear portionof the third bus bar 632 and the rear portion of the fourth bus bar 642to the sixth surface is greater than 0.5. In this embodiment, the arearatio of the overlapping area to the fifth surface and the area ratio ofthe overlapping area to the sixth surface may be different. In order tofurther ensure a good parasitic inductance reduction effect, the arearatios of the overlapping area of the rear portion of the third bus barand the rear portion of the fourth bus bar to the fifth surface and thesixth surface may both be 1, which may further effectively reduce theparasitic inductance. That is, the rear portion of the third bus bar 632and the rear portion of the fourth bus bar 642 are overlapped inparallel, and surface areas of the oppositely disposed surfaces areequal.

As shown in FIG. 6, in the present exemplary embodiment, the frontportion of the third bus bar 631 is provided with a third connectingterminal 635, and the third connecting terminal 635 is stacked andconnected with the second connecting terminal 625. The rear portion ofthe fourth bus bar 641 is provided with a. fourth connecting terminal645, and the fourth connecting terminal 645 is stacked and connectedwith the first connecting terminal 615. For example, the thirdconnecting terminal 635 and the second connecting terminal 625 may beelectrically connected by mechanical fixing or the like, and the fourthconnecting terminal 645 and the first connecting terminal 615 may alsobe electrically connected by mechanical fixing or the like.

FIG. 6 further shows the schematic diagram of the flow direction of thecurrent in each part of the component structure 600, wherein the flowdirection of the current is indicated by the dashed arrow in FIG. 6. Itis assumed that the current flows from the first bus bar 610 into thepower module and flows out from the second bus bar 620. As shown in FIG.6, the current of the external circuit flows to the fourth connectingterminal 645 through the fourth bus bar 640. The fourth connectingterminal 645 is connected with the first connecting terminal 615, andthe current flows into the first bus bar 610 through the firstconnecting terminal 615. Then, the current is switched from the firstbus bar 610 to the second bus bar 620 through the circuit distributiondesign inside the power module and flows out from the second bus bar620. The second connecting terminal 625 is connected with the thirdconnecting terminal 635, and the current flows into the third connectingterminal 635 through the second connecting terminal 625, and then flowsinto the external circuit through the third bus bar 630. A wiring layerof the external circuit is not shown in detail, and it may usuallyimplemented by a laminated bus bar, a PCB or a laminated copper bar, butnot limited thereto. It should be noted that bus bar areas of the upperand lower layers shown in FIG. 6 are strictly identical, but inpractice, since some electrodes need to be connected to a certain layerof the laminated bus bars, some avoidance space may need to be remained,resulting in that the bus bar areas of the upper and lower layers do nothave o be strictly identical. Those skilled in the art may determine itflexibly according to needs, and no special explanation will be givenhere.

From the above, in the present exemplary embodiment, a currentconducting direction of the front portion of the first bus bar 611 isopposite to that of the front portion of the second bus bar 621, acurrent conducting direction of the rear portion of the first bus bar612 is opposite to that of the front portion of the fourth bus bar 641,a current conducting direction of the rear portion of the second bus bar622 is opposite to that of the front portion of the third bus bar 631,and a current conducting direction of the rear portion of the third busbar 632 is opposite to that of the rear portion of the fourth bus bar642. The effect of reverse currents to cancel out each other issignificant, and the parasitic inductance may be greatly reduced.

In addition, similar to the exemplary embodiment of FIG. 4, the rearportion of the second bus bar 622 may also be provided with a bendingportion, such that the first plane A and the second plane B are locatedin the same plane. The front portion of the third bus bar 631 may alsobe provided with a bending portion, such that the front portion of thethird bus bar 631 and the front portion of the fourth bus bar 641 are inthe same plane, so that the interlayer distance can be further reduced,and then the parasitic inductance can be further reduced, which will notbe described again herein.

It should be noted that only main structures of the component structure600 are described in FIG. 6, in which the insulating layer is not shown,and the thickness, width and the like of the bus bar are alsoschematically depicted instead of being drawn in scale.

In the exemplary embodiments described above, the connecting terminalsare all stacked and connected with each other, but the presentdisclosure is not limited thereto. In other exemplary embodiments of thepresent disclosure, the connecting terminals may also be in other forms,and other connecting manners may also be adopted correspondingly.

Referring to FIG. 7, in one exemplary embodiment of the presentdisclosure, inside the power module, one end of the first bus bar 710extends to the first plane A and the first connecting terminals 715 areformed. The first connecting terminals 715 are plug-in type terminals.The second bus bar 720 includes a front portion of the second bus bar721 and a rear portion of the second bus bar 722, and the front portionof the second bus bar 721 and the rear portion of the second bus bar 722are connected. The front portion of the second bus bar 721 and the firstbus bar 710 are laminated. in parallel. The rear portion of the secondbus bar extends to the second plane B, and the second connectingterminals 725 are formed. The second connecting terminals 725 areplug-in type terminals. The first connecting terminals 715 and thesecond connecting terminals 725 are served as connecting ports betweenthe power module and the external circuit. The external circuit includesa third bus bar 730 and a fourth bus bar 740. The third bus bar 730 hasa front portion of the third bus bar 731 and a rear portion of the thirdbus bar 732. The front portion of the third bus bar 731 and the rearportion of the second bus bar 722 are settled in parallel, and the frontportion of the third bus bar 731 is a portion of the third bus bar 730disposed opposite to the rear portion of the second bus bar 722. Thefourth bus bar 740 is laminated in parallel with the rear portion of thethird bus bar 732. The parasitic inductance between the first connectingterminals 715 and the second connecting terminals 725 can be reducedthrough these stack settings. It should be noted that only partialstructures of the third bus bar and the fourth bus bar are shown in thefigure, and the third bus bar and the fourth bus may have a larger areaand length to connect other elements of the external circuit. Sincethese structures are weakly related to the present disclosure, they arenot shown in detail.

Further, surfaces of the rear portion of the second bus bar 722. and thefront portion of the third bus bar 731 settled in parallel are a firstsurface and a second surface respectively. An area ratio of anoverlapping area of the rear portion of the second bus bar 722 and thefront portion of the third bus bar 731 to the first surface is greaterthan 0.5. In order to further ensure a good parasitic inductancereduction effect, an area ratio of the overlapping area of the rearportion of the second bus bar and the front portion of the third bus barto the first surface may be 1. In order to further ensure a goodparasitic inductance reduction effect, area ratios of the overlappingarea. of the rear portion of the second bus bar and the front portion ofthe third bus bar to the first surface and the second surface may bothbe 1, which may further effectively reduce the parasitic inductance.That is, the rear portion of the second bus bar 722 and the frontportion of the third bus bar 731 are overlapped in parallel, and surfaceareas of the oppositely disposed surfaces are equal.

Similarly, surfaces of the fourth bus bar 740 and the rear portion ofthe third bus bar 732 disposed oppositely are respectively a thirdsurface and a fourth surface. An area ratio of an overlapping area ofthe rear portion of the third bus bar 732 and the fourth bus bar 740 tothe third surface is greater than 0.5, and an area ratio of anoverlapping area of the rear portion of the third bus bar 732 and thefourth bus bar 740 to the fourth surface is greater than 0.5. In thisembodiment, the area ratio of the overlapping area to the third surfaceand the area ratio of the overlapping area to the fourth surface may bedifferent. In order to further ensure a good parasitic inductancereduction effect of the external circuit, the area ratios of theoverlapping area of the rear portion of the third bus bar and the rearportion of the fourth bus bar to the third surface and the fourthsurface may both be 1, which may further effectively reduce theparasitic inductance. That is, the rear portion of the third bus bar 732and the fourth bus bar 740 are overlapped in parallel, and surface areasof the oppositely disposed surfaces are equal.

As shown in FIG. 7, in the present exemplary embodiment, the frontportion of the third bus bar 731 is provided with the third connectingterminals 735, and the third connecting terminals 735 are connected withthe first connecting terminals 715 in one to one ratio. The fourth busbar 740 is provided with the fourth connecting terminals 745, and thefourth connecting terminals 745 are connected with the second connectingterminals 725 in one to one ratio. Both the third connecting terminals735 and the fourth connecting terminals 745 may be terminals that can bemated Ti the plug-in type terminals. For example, the third connectingterminals 735 and the first connecting terminals 715 can be electricallyconnected by welding or press-fit or the like. The fourth connectingterminals 745 and the second connecting terminals 725 can also beelectrically connected by welding or press-fit or the like.

FIG. 7 further shows the schematic diagram of the flow direction of thecurrent in each part of the component structure 700, wherein the flowdirection of the current is indicated by the dashed arrow in FIG. 7. itis assumed that the current flows from the first bus bar 710 into thepower module and flows out from the second bus bar 720, As shown in FIG.7, the current of the external circuit flows to the third connectingterminal 735 through the third bus bar 730. The first connectingterminal 715 is connected to the third connecting terminal 735, and thecurrent flows into the first bus bar 710 through the first connectingterminal 715. The current is then switched from the first bus bar 710 tothe second bus bar 720 through the circuit distribution design insidethe power module and flows out from the second bus bar 720. The currentflows into the fourth connecting terminal 745 through the secondconnecting terminal 725, and then flows into the external circuitthrough the fourth bus bar 740. A wiring layer of the external circuitis not shown in detail, and it may usually implemented by a laminatedbus bar, a PCB or a laminated copper bar, but not limited thereto. Itshould be noted that bus bar areas of the upper and lower layers shownin FIG. 7 are strictly identical, but in practice, since some electrodesneed to be connected to a certain layer of the laminated bus bars, someavoidance space may need to be remained. For example, through holes andthe like for avoiding the second connecting terminals 725 needs to beset on the third bus bar 730. It results in that the bus bar areas ofthe upper and lower layers do not have to be strictly identical. Thoseskilled in the art may determine it flexibly according to needs, and nospecial explanation will be given here.

In the present exemplary embodiment, the first bus bar 710 overlaps withthe front portion of the second bus bar 721, and the interlayer distanceis relatively small. Due to limitations of voltage isolation andmaterial or the like, the thickness of the bus bar is generally between20 μm and 500 μm. Because the direction of the current inside the firstbus bar 710 is opposite to that of the current inside the front portionof the second bus bar 721, the loop inductance of this portion isrelatively low, which may be usually limited to between 0˜9 nH. Due toconsiderations of voltage isolation or the like, a distance of the rearportion of the second bus bar 722 is relatively long (usually greaterthan 5 mm), resulting in a large parasitic inductance, which is usuallylarger than 10 nH. Thus the rear portion of the second bus bar 722becomes a major factor affecting the loop inductance. However, in thepresent exemplary embodiment, since the front portion of the third busbar 731 of the external circuit and the rear portion of the second busbar 722 are superimposed in parallel or overlapped in parallel with a.large overlapping area, and the current direction of the front portionof the third bus bar 731 is opposite to that of the rear portion of thesecond bus bar 722, the loop inductance can be partially or completelycounteracted, so that its parasitic inductance is greatly reduced.

From the above, in the present disclosure, a current conductingdirection of the first bus bar 710 is opposite to that of the frontportion of the second bus bar 721, a current conducting direction of therear portion of the second bus bar 722 is opposite to that of the frontportion of the third bus bar 731, and a current conducting direction ofthe rear portion of the third bus bar 732 is opposite to that of thefourth bus bar 740. The counteracting effect of the opposite currents issignificant, and the parasitic inductance can be greatly reduced. Theoverall circuit parasitic inductance of the component structure 700 isgreatly reduced. Therefore, the present disclosure effectively solvesthe problem of large circuit inductance through the design of alaminated bus bar inside the power module and the cooperation with thebus bar of the external circuit.

In addition, similar to the exemplary embodiment in FIG. 4, the firstbus bar 710 further includes a first extending portion 711 and a firstbending portion 712. The first bending portion 712 is located in thefirst plane A. The first connecting terminals 715 are disposed at an endof the first bending portion 712. The front portion of the second busbar 721 further includes a second extending portion 7211 and a secondbending portion 7212. The first extending portion 711 and the secondextending portion 7211 are laminated in parallel, and the first bendingportion 712 and the second bending portion 7212 are laminated inparallel. The rear portion of the second bus bar further includes athird extending portion 7221 and a third bending portion 7222. The thirdbending portion 7222 is connected to the second bending portion 7212,and the third extending portion 7221 is located in the second plane B.The second connecting terminals 725 are disposed at an end of the thirdextending portion 7221, which will not be described again here.

It should be noted that only main structures of the component structure700 are described in FIG. 7, in which the insulating layer is not shown,and the thickness, width and the like of the bus bar are alsoschematically depicted instead of being drawn in scale.

In the previous exemplary embodiments, the corresponding power modulesare two-port structures, and there are two output terminals. A typicalapplication of the power module may be the half-bridge power circuitwith capacitor clamping as shown in FIG. 1, a half-bridge power circuitwith diode clamping as shown in FIG. 8, a half-bridge power circuit withactive clamping as shown in FIG. 9 and the like. These typicalapplications will be described in detail below

The half-bridge circuit with capacitor clamping as shown in FIG. 1 istaken as an example, in Which a first IGBT element S1 and a second IGBTelement S2 are connected in parallel with a diode D1 and a diode D2respectively, then connected in series, and then the bridge arm circuitformed by the series connection is further connected in parallel withthe capacitor C of the external clamping circuit. The capacitor C caneffectively reduce the voltage spike between a collector of the firstIGBT element S1 and an emitter of the second IGBT element S2 duringswitching. For example, when the first IGBT element SI is turned on andthe second IGBT element S2 is turned off, the capacitor C can reduce thevoltage between the collector and the emitter of the second IGBT elementS2. When the first IGBT element S1 is turned off and the second IGBTelement S2 is turned on, the capacitor C can reduce the voltage betweenthe collector and the emitter of the first IGBT element S1. At the sametime, the parasitic inductance of the current loop composed of the firstIGBT element S1, the second IGBT element S2 and the capacitor C needs tobe strictly controlled. In view of this, in the present embodiment, thecollector of the first IGBT element Si and the emitter of the secondIGBT element S2 may be respectively led to the first connecting terminaland the second connecting terminal which are the ports of the powermodule through the first bus bar and the second bus bar, and connectedto the capacitor C of the external circuit through the third connectingterminal and the fourth connecting terminal. The connection between thepower module and the external circuit is realized through the componentstructure in the above exemplary embodiment, and a low loop parasiticinductance can be obtained, thereby reducing the voltage stressexperienced by the power elements and improving the efficiency of thecircuit.

Referring to FIG. 8, a schematic diagram of a half-bridge power circuitwith diode clamping is shown. The circuit connection is basically thesame as the half-bridge circuit with capacitor clamping as shown in FIG.1 except that the capacitor C in FIG. 1 is replaced by a diode clampingcircuit 801. The diode clamping circuit 801 includes a capacitor C1 adiode D and a snubber resistor R. Similarly, the parasitic inductance ofthe current loop composed of the first IGBT element S1, the second IGBTelement S2 and the diode D needs to be strictly controlled. In view ofthis, in the present embodiment, the collector of the first IGBT elementS1 and the emitter of the second IGBT element S2 may be respectively ledto the first connecting terminal and the second connecting terminalwhich are the ports of the power module through the first bus bar andthe second bus bar, and connected to the capacitor C1 of the externalcircuit and the diode D through the third connecting terminal and thefourth connecting terminal. The connection between the power module andthe external circuit is realized through the component structure in theabove exemplary embodiment, and a low loop parasitic inductance can heobtained, thereby reducing the voltage stress experienced by the powerelement and improving the efficiency of the circuit.

Referring to FIG. 9, a schematic diagram of a half-bridge power circuitwith active clamping is shown. The circuit connection is basically thesame as the half-bridge circuit with capacitor clamping as shown in FIG.1 except that the capacitor C in FIG. 1 is replaced by an activeclamping circuit 901. The active clamping circuit 901 includes acapacitor C2, a power semiconductor element S and a snubber resistor R.Similarly, the parasitic inductance of the commutation loop composed ofthe first IGBT element S1, the second IGBT element S2, the capacitor C2and the power semiconductor element S needs to be strictly controlled.In view of this, in the present embodiment, the collector of the firstIGBT element Si and the emitter of the second IGBT element S2 may berespectively led to the first connecting terminal and the secondconnecting terminal which are the ports of the power module through thefirst bus bar and the second bus bar, and connected to the capacitor C2of the external circuit and the power semiconductor element S throughthe third connecting terminal and the fourth connecting terminal. Theconnection between the power module and the external circuit is realizedthrough the component structure in the above exemplary embodiment, and alow loop parasitic inductance can be obtained, thereby reducing thevoltage stress experienced by the power element and improving theefficiency of the circuit.

It should be noted that all or some of the elements of the clampingcircuits may be disposed on the internal laminated bus bar or on theexternal circuit unit. Persons of ordinary skill in the art can changethe form of the internal laminated bus bars slightly as needed. Forexample, as shown in FIG. 10, a wiring layer 480 of the mountingelements 490 can be added additionally, to achieve the placement of theelements 490. As another example, as shown in FIG. 11, it is alsopossible to allocate the partial position of a layer in the internallaminated bus bars to the same surface of another layer by rewiring, soas to directly mount the elements 490 through the SMT (Surface MountTechnology) process. As still another example, as shown in FIG. 12, theelements 490 can also be mounted on a layer of the laminated bus bars,and a partial position of another layer of the laminated bus bars isexposed, and the electrical connection is achieved by a wire bondingprocess. In addition, it is easily understood that, circuit elements forrealizing other functions, such as a driving circuit or the like, mayalso be mounted on the internal laminated bus bar, which is notparticularly limited in this exemplary embodiment. In addition, thelaminated bus bars may also lead out other signal terminals in additionto the power terminals, which will not be described in detail herein.

In the following exemplary embodiments, the corresponding power modulesare all three-port structures, that is, there are three outputterminals, which will be described in detail below.

Referring to FIG. 13, in the component structure 1300 of one exemplaryembodiment of the present disclosure, inside the power module, inaddition to the first bus bar 1310 and the second bus bar 1320, a fifthbus bar 1350 is further included. In the embodiment, one end of thefirst bus bar 1310 extends to a first plane A and a first connectingterminal 1315 is formed. The second bus bar 1320 includes a frontportion of the second bus bar 1321 and a rear portion of the second busbar 1322. The front portion of the second bus bar 1321 and a rearportion of the second bus bar 1322 are connected. The front portion ofthe second bus bar 1321 is laminated in parallel with the first bus bar1310. The rear portion of the second bus bar 1322 extends to a secondplane B and a second connecting terminal 1325 is formed. The fifth busbar 1350 includes a front portion of the fifth bus bar 1351 and a rearportion of the fifth bus bar 1352.. The front portion of the fifth busbar 1351 and the rear portion of the fifth bus bar 1352 are connected.The front portion of the fifth bus bar 1351 is laminated in parallelwith the first bus bar 1310. The rear portion of the fifth bus bar 1352extends to a third plane C and a fifth connecting terminal 1355 isformed. The first connecting terminal 1315, the second connectingterminal 1325 and the fifth connecting terminal 1355 are served asconnecting ports between the power module and the external circuit. Theexternal circuit includes a third bus bar 1330 and a fourth bus bar1340. The third bus bar 1330 is settled in parallel with the rearportion of the second bus bar 1322, to reduce the parasitic inductancebetween the first connecting terminal 1315 and the second connectingterminal 1325. The fourth bus bar 1340 is settled in parallel with therear portion of the fifth bus bar 1352, to reduce the parasitic induct,between the first connecting terminal 1315 and the fifth connectingterminal 1355,

It should be noted that only the partial structures of the third bus barand the fourth bus bar are shown in the figure, and the third bus barand the fourth bus bar may have a larger area and length to connectother elements of the external circuit. Since the subsequent structuresare weakly related to the present disclosure, they are not shown indetail.

A portion of the third bus bar 1330 disposed opposite to the rearportion of the second bus bar 1322 is further defined as a front portionof the third bus bar. Surfaces of the rear portion of the second bus bar1322 and the front portion of the third bus bar disposed oppositely area first surface and a second surface respectively. An area ratio of anoverlapping area of the rear portion of the second bus bar 1322 and thefront portion of the third bus bar to the first surface is greater than0.5, and an area ratio of an overlapping area of the rear portion of thesecond bus bar 1322 and the front portion of the third bus bar to thesecond surface is greater than 0.5. In this embodiment, the area ratioof the overlapping area to the first surface and the area ratio of theoverlapping area to the second surface may be different. In order tofurther ensure a good parasitic inductance reduction effect, the arearatios of the overlapping area of the rear portion of the second bus barand the front portion of the third bus bar to the first surface and thesecond surface may both be 1, which may further effectively reduce theparasitic inductance. That is, the rear portion of the second bus bar1322 and the front portion of the third bus bar are overlapped inparallel, and surface areas of the oppositely disposed surfaces areequal.

Similarly, a portion of the fourth bus bar 1340 disposed opposite to therear portion of the fifth bus bar 1352 is further defined as a frontportion of the fourth bus bar. Surfaces of the rear portion of the fifthbus bar 1352 and the front portion of the fourth bus bar disposedoppositely are a third surface and a fourth surface respectively. Anarea ratio of an overlapping area of the rear portion of the fifth busbar 1352 and the front portion of the fourth bus bar to the thirdsurface is greater than 0.5, and an area ratio of an overlapping area ofthe rear portion of the fifth bus bar 1352 and the front portion of thefourth bus bar to the fourth surface is greater than 0.5. In thisembodiment, the area ratio of the overlapping area to the third surfaceand the area ratio of the overlapping area to the fourth surface may bedifferent. In order to further ensure a good parasitic inductancereduction effect, the area ratios of the overlapping area of the rearportion of the fifth bus bar and the front portion of the fourth bus barto the third surface and the fourth surface may both be 1, which mayfurther effectively reduce the parasitic inductance. That is, the rearportion of the fifth bus bar 1352 and the front portion of the fourthbus bar are overlapped in parallel, and surface areas of the oppositelydisposed surfaces are equal.

As shown in FIG. 13, in the present exemplary embodiment, one end of thethird bus bar 1330 is provided with a third connecting terminal 1335,and the third connecting terminal 1335 is stacked and connected with thesecond connecting terminal 1325. For example, the third connectingterminal 1335 and the second connecting terminal 1325 can beelectrically connected by mechanical fixing or the like. One end of thefourth bus bar 1340 is provided with a fourth connecting terminal 1345,and the fourth connecting terminal 1345 is stacked and connected withthe fifth connecting terminal 1355. For example, the fourth connectingterminal 1345 and the fifth connecting terminal 1355 can be electricallyconnected by mechanical fixing or the like. The external circuit isfurther provided a sixth connecting terminal 1365, and the sixthconnecting terminal 1365 and the first connecting terminal 1315 arestacked and connected. For example, the sixth connecting terminal 1365and the first connecting terminal 1315 may be electrically connected bymechanical fixing or the like through a through hole avoided in thethird bus bar 1330 and the fifth bus bar 1350.

FIG. 13 further shows the schematic diagram of the flow direction of thecurrent in each part of the component structure 1300, wherein the flowdirection of the current is indicated by the washed arrow in FIG. 13. Asfor a three-port element, there are two loop current paths. The firstloop current path is as follows: the external current flows into thefirst bus bar 1310 inside the module through the sixth connectingterminal 1365, and flows out from the second connecting terminal 1325 ofthe second bus bar 1320 and then flows into the third bus bar 1330. Theother loop current path is as follows: the external current flows intothe first bus bar 1310 inside the module through the sixth connectingterminal 1365, and flows out from the fifth connecting terminal 1355 ofthe fifth bus bar 1350, and then flows into the fourth bus bar 1340.Specifically, continuing to refer to FIG. 13, as for the first loopcurrent path, the current of the external circuit flows to the firstconnecting terminal 1315 via the sixth connecting terminal 1365; thecurrent flows into the first bus 1310 through the first connectingterminal 1315; then the current is switched from the first bus bar 1310to the second bus bar 1320 through the circuit distribution designinside the power module, and flows out from the second bus bar 1320; thecurrent flows into the third connecting terminal 1335 through the secondconnecting terminal 1325, and the current flows into the third bus bar1330 through the third connecting terminal 1335. and then flows into theexternal circuit through the third bus bar 1330. As for the second loopcurrent path, as shown in FIG. 13, the current of the external circuitflows to the first connecting terminal 1315 via the sixth connectingterminal 1365; the current flows into the first bus bar 1310 through thefirst connecting terminal 1315; then the current is switched from thefirst bus bar 1310 to the fifth bus bar 1350 through the circuitdistribution design inside the power module, and flows out from thefifth bus bar 1350; the current flows into the fourth bus bar 1345through the fifth connecting terminal 1355, and then flows into thefourth bus bar 1340 through the fourth connecting terminal 1345 and thenflows into the external circuit. A wiring layer of the external circuitis not shown in detail, and it may usually implemented by a laminatedbus bar, a PCB or a laminated copper bar, but not limited thereto. Itshould be noted that bus bar areas of the upper and lower layers shownin FIG. 13 are strictly identical, but in practice, since someelectrodes need to be connected to a certain layer of the laminated busbars, some avoidance space may need to be remained, resulting in thatthe bus bar areas of the upper and lower layers do not have to bestrictly identical. Those skilled in the art may determine it flexiblyaccording to needs, and no special explanation will be given here.

From the above, in the present disclosure, a current conductingdirection of the first bus bar 1310 is opposite to that of the frontportion of the second bus bar 1321, a current conducting direction ofthe first bus bar 1310 is opposite to that of the front portion of thefifth bus bar 1351, a current conducting direction of the rear potion ofthe second bus bar 1322 is opposite to that of the third bus bar 1330,and a current conducting direction of the rear portion of the fifth busbar 1352 is opposite to that of the fourth bus bar 1340. Sinceconducting directions of the current are opposite and the counteractingeffect of the opposite currents is significant, the parasitic inductancecan be greatly reduced.

In addition, similar to the previous exemplary embodiment in FIG. 4, therear portion of the second bus bar 1322 may also be provided with abending portion, such that the first plane A and the third plane C arelocated in the same plane. The interlayer distance can be furtherreduced, and then the parasitic inductance can be further reduced, whichwill not be described again herein.

In the above-described exemplary embodiment of FIG. 13, the first busbar 1310 is disposed between the front portion of the second bus bar1321 and the front portion of the fifth bus bar 1351, but in otherexemplary embodiments of the present disclosure, it is also possible toadopt other settings.

As shown in FIG. 14, in one exemplary embodiment of the presentdisclosure, the front portion of the second bus bar 1321 and the frontportion of the fifth bus bar 1351 of the component structure 1300 arearranged in parallel. That is, the front portion of the second bus bar1321 and the front portion of the fifth bus bar 1351 are disposed in thesame layer. By arranging the front portion of the second bus bar 1321and the front portion of the fifth bus bar 1351 in parallel, thethickness of the power module can be reduced, thereby facilitating therealization of an ultrathin product. The other parts of the componentstructure in this exemplary embodiment are similar to those of theprevious exemplary embodiment of FIG. 13, and thus will not be describedagain here.

In the previous exemplary embodiments in FIGS. 13 and 14, thecorresponding power modules are all three-port structures. There arethree output terminals. A typical application of the power module may bea three-level circuit with a clamping circuit as shown in FIG. 15, or aI-type three-level power circuit with a snubber capacitor as shown inFIG. 16. These typical applications will be described in detail below.

Referring to FIG. 15, a schematic diagram of a three-level power circuitwith a clamping circuit is shown. A first IGBT element S1, a second IGBTelement S2, a third IGBT element S3, and a fourth IGBT element S4 areconnected in parallel with a diode D1, a diode D2, a diode D3 and adiode D4 respectively, and then connected in series to form a bridge armcircuit. The bridge arm circuit is connected in parallel with a branchcircuit formed by connecting the capacitor C1 and the capacitor C2 inseries. The branch circuit formed by series connection of the third IGBTelement S3 and the fourth IGBT element S4 in the bridge arm circuit isconnected in parallel with the branch circuit formed by connecting thediode D5 and the diode D6 in series. A connection point (hereinafterreferred to as a common terminal) of the capacitor C1 and the capacitorC2 is connected with a connection point of the diode Di and the diodeD6. In this circuit, the capacitor C1 as a control element can reducethe voltage spike between the collector of the first IGBT element S1 andthe anode of the diode D5 during switching. For example, when the firstIGBT element S1 is turned on and the diode D5 is reversely blocked, thecapacitor CI can reduce the voltage between the anode and cathode of thediode D5. When the diode D5 is conducting forward and the first IGBTelement S1 is turned off, the capacitor C1 can reduce the voltagebetween the collector and the emitter of the first IGBT element S1. Thecapacitor C2 as a control element can reduce the voltage spike betweenthe emitter of the fourth IGBT element S4 and the cathode of the diodeD6. For example, when the fourth IGBT element S4 is turned on and thediode D6 is reversely blocked, the capacitor C2 can reduce the voltagebetween the anode and cathode of the diode D6. When the diode D6 isconducting forward and the fourth IGBT element S4 is turned off, thecapacitor C2 can reduce the voltage between the collector and theemitter of the fourth IGBT element S4. At the same time, the parasiticinductance of the commutation loop composed of the first IGBT elementS1, the diode D5, and the capacitor C1 and the current loop composed ofthe fourth IGBT element S4, the diode D6, and the capacitor C2 needs tobe strictly controlled. In view of this, in the present embodiment, thecollector of the first IGBT element S1 and the emitter of the fourthIGBT element S4 may be respectively connected to the second connectingterminal and the fifth connecting terminal of the power module throughthe second bus bar and the fifth bus bar, and connected to thecapacitors C1 and C2 of the external circuit through the thirdconnecting terminal and the fourth connecting terminal. The commonterminal can be connected to the first connecting terminal of the powermodule via the first bus bar, and connected to the external circuitthrough the sixth connecting terminal. The connection between the powermodule and the external circuit is realized through the componentstructure in the above exemplary embodiment, and a low loop parasiticinductance can be obtained, thereby reducing the voltage stressexperienced by the power element and improving the efficiency of thecircuit.

Referring to FIG. 16, a schematic diagram of a T-type three-level powercircuit with a snubber capacitor is shown. A first IGBT element S1 asecond IGBT element S2 are connected in parallel with a diode D1, adiode D2 respectively, and then connected in series to form a bridge armcircuit. The bridge arm circuit is connected in parallel with a branchcircuit formed by connecting the capacitor C1 and the capacitor C2 inseries. The third IGBT element S3 and the fourth IGBT element S4 areconnected in parallel with the diodes D3 and D4 respectively, and thenconnected in series to form a branch circuit. The branch circuit isconnected in series between a midpoint of the bridge circuit and aconnection point (hereinafter referred to as a common terminal) of thecapacitor C1 and the capacitor C2. Specifically, it may be the case thatthe emitter of the third IGBT element S3 is connected to the commonterminal, and the collector of the fourth IGBT element S4 is connectedto the midpoint of the bridge arm circuit. Similarly, the parasiticinductance of the current loop composed of the first IGBT element S1,the fourth IGBT element S4, the diode D3, and the capacitor C1 and thecurrent loop composed of the second IGBT element S2, the third IGBTelement S3, the diode D4, and the capacitor C2 needs to be strictlycontrolled. In view of this, in the present embodiment, the collector ofthe first IGBT element S1 and the emitter of the second IGBT element S2may be respectively connected to the second connecting terminal and thefifth connecting terminal of the power module through the second bus barand the fifth bus bar, and connected to the capacitors C1 and C2 of theexternal circuit through the third connecting terminal and the fourthconnecting terminal. The common terminal can be connected to the firstconnecting terminal of the power module via the first bus bar, andconnected to the external circuit through the sixth connecting terminal.The connection between the power module and the external circuit isrealized through the component structure in the above exemplaryembodiment, and a low loop parasitic inductance can be obtained, therebyreducing the voltage stress experienced by the power element andimproving the efficiency of the circuit.

From the typical application of the power modules in the above exemplaryembodiments, it can be seen that the power modules applied in thepresent disclosure generally includes at least two power elementsconnected in series, and at least one of the power elements is acontrollable element, such as an MOSFET, an IGBT, a SiC MOS, a GaN MOS.The basic features of the controllable element are all controllablethree-port power elements including a first terminal, a second terminal,and a control terminal. Another power element can be a controllableelement or an uncontrollable element, such as a diode or the like.Therefore, the component structure in the present disclosure has a widerange of applications, for example, it can be widely applied to powerconversion equipment such as solar inverters, uninterruptible powersupplies, active filters, and motor drives.

Further, a power module is also provided in an exemplary embodiment ofthe present disclosure. The power module may include a substrate a powerunit, and a component structure in any one of the above-describedexemplary embodiments. In the embodiment, the power unit is disposed onthe substrate, and the component structure connects the power unit andan external circuit. The power module will be further described belowwith reference to FIGS. 17 and 18.

Referring to FIG. 17, the substrate may be a DBC (Direct BondingCopper). However, in other exemplary embodiments of the presentdisclosure, the substrate may also be an Active Metal Bonding (AMB), anInsulated Metal Substrate (IMS), a Direct Plated Copper (DPC) or a thickfilm circuit and so on. In addition, in order to improve the heatdissipation performance of the power module, a heat dissipationstructure, such as a heat sink, a fin, a boss and the like may beintegrated at one side of the substrate where a device is not mounted.

The power unit may include a power element S1 and a power element S2provided on a DBC substrate. The power element S1 and the power elementS2 may be disposed on the substrate DBC through a die bonding materiallayer 1702. The material of the die bonding material layer 1702 may be abrazing material, a low temperature sintering material, a conductiveadhesive, or the like, which is not specifically limited in the presentexemplary embodiment. The power element S1 and the power element S2 areconnected in series. The first end of the power unit may be one end ofthe power element S1, such as the drain electrode of the power elementS1. The second end of the power unit may be one end of the power elementS2, such as the source electrode of the power element S2.

The component structure 1700 includes two layers of laminated bus bars,which may be the first bus bar and the second bus bar respectively inthe previous exemplary embodiment of FIG. 4. The lower layer of thelaminated bus bars may be mechanically and thermally connected to thesubstrate DBC through the adhesive material layer 1701. An insulatingmedium such as a ceramic is provided between two layers of the laminatedbus bars. When the insulating medium is a ceramic, the ceramic materialmay be aluminum oxide, aluminum nitride, silicon nitride, siliconcarbide, and beryllium oxide or the like. This is not particularlylimited in the exemplary embodiment.

The power unit is connected to the component structure. For example, thefirst end (front electrode) of the power element S1 is connected to thewiring layer of the substrate DCB through the lead 1703. and the secondend (back electrode) of the power element S1 is connected to the lowerlayer of the laminated bus bars through the lead 1705. The first end ofthe power element S2 is connected to the upper layer of the laminatedbus bars through the lead 1704, and the second end of the power elementS2 is led out through the wiring layer of the substrate DCB.Specifically, referring to FIGS. 17 and 2, it can be the case that thesource electrode of the power element S1 is connected to the wiringlayer of the substrate DBC through the bonding wire 1703, and the drainelectrode of the power element S1 is connected to the lower layer of thelaminated bus bars through the lead 1705. The source electrode of thepower element S2 is connected to the upper layer of the laminated busbars through a bonding wire 1704, and the drain electrode is connectedto the DCB wiring layer of the substrate. However, it is easy tounderstand that other feasible connection manners also fall within theprotection scope of the present disclosure.

It should be noted that the material for insulation protection is notshown in the power module shown in FIG. 17. The insulation protectionmaterial can guarantee the voltage withstand requirements between thechip and the electrical connection unit. There are two kinds of typicalprotection manners in the art. One is the potting insulation protectionmaterial, and the other is transfer molding the insulating protectionmaterial, both of which are within the protection scope of the presentdisclosure.

In addition, for the purpose of insulation, it is also possible to coverthe surface of the laminated bus bar with a high-voltage insulatingmaterial and open a window in a part that needs to be electricallyconnected with the outside. The above content can be referred to theprior art and is not shown in detail in the figure. The control terminalof the power element or the like are not shown in the figure either,which can also refer to the prior art. In addition, in practicalapplications, the laminated bus bars may not be limited to one unit, butmay have a plurality of double-layered structures, to achieve differentcurrents and circuit requirements. The surface of the laminated bus barsmay also set graphic regions according to circuit requirements. Inaddition, components and parts, such as a gate resistor, a driver chip,and the like are provided thereon, which is not specifically limited inthis exemplary embodiment.

It should be noted that in FIG. 17, the two-layer laminated bus bar istaken as an example for description. However, when the power unit alsohas the third terminal and is a three-port structure, the laminated busbar may also be set as three layers. For example, the third layer of thelaminated bus bars may be the fifth bus bar in the above exemplaryembodiment, and the third end of the power unit is connected with thefifth bus bar. Alternatively, the laminated bus bar is provided in twolayers, but one of the layers is provided to be two bus bars arranged inparallel, and the additionally arranged bus bar may be the fifth bus barin the above exemplary embodiment, and the third terminal of the powerunit is connected to the fifth bus bar.

In the above power module, the insulation between the power moduleterminal and the external circuit also needs to be considered, Referringto FIG. 18, a partial structure of the laminated bus bars inside thepower module is shown in the solid box, and a partial structure of theexternal circuit (such as the above-mentioned third bus bar, the fourthbus bar, etc.) is shown in the dashed box. The distance d between thepartial structure of the laminated bus bar inside the power module andthe partial structure of the external circuit is only for indicatingthat the two are separated in the figure. In actual use, the twostructures will be closely fit together by mechanical compression or thelike, to obtain better loop inductance.

Further, in order to ensure a good inductance control effect, athickness of the surface insulating layer located between the above two(for example, between the third bus bar and the rear portion of thesecond bus bar, or between the fourth bus bar and the rear portion ofthe fifth bus bar) is generally less than 0.5 mm. In the presentexemplary embodiment, it is less than 0.2 mm preferably. At the sametime, in order to ensure a good insulation effect, the surfaceinsulation layer can be laminated by two insulation layers or even moreinsulation layers, thereby avoiding the failure of voltage isolationcaused by cutthrough at the same position due to raw materials andprocess defects. The material of the surface insulating layer may bepolyester, polyimide, epoxy resin, polyvinyl fluoride, silicone and notlimited thereto. In addition, as for the insulating layer of the samematerial, the insulating distance X in the figure is greater than 0.2mm, and preferably greater than 0.4 mm. In addition, the insulationtreatment of the surface of the laminated. bus bars and the insulationedge of the metal edge covering can also be performed. This section canrefer to the prior art and will not be described again here.

In FIG. 18. the current direction may flow from the D position to the Eposition and then flow into the terminal F of the power module. Afterbeing distributed by the internal circuit of the power module, thecurrent flows from the I position and flows to the terminal J of themodule, and then flows to the external allocation unit K. In the above Fposition, it is necessary to realize the conversion of the bus bars ofdifferent layers, to lift the pin terminals to the same plane. in thecase of a small current, the thickness of the laminated bus bars isusually relatively thin, and each pin terminal can be lifted to the sameplane by through-hole plating. However, in the case of a large current,on the one hand, the thickness of the electroplating layer itself islimited and it is difficult to apply to a large current. On the otherhand, the thickness of the laminated bus bar itself is also large, so itis difficult to use the through-hole plating manner to raise each pinterminal to the same plane. Based on this, a pin terminal (such as aT-type pin terminal, etc.) may be directly riveted to the lower layer ofthe laminated bus bars, so that all the pin terminals can reach the sameplane. Of course, a metal gasket may also be directly provided on thelower layer of the laminated bus bars, to lift the pin terminals to thesame plane. The metal gasket can be fixed on the lower layer of thelaminated bus bars by the connecting material (such as conductiveadhesive, welding material, etc.), or the metal gasket can be directlyplaced in the corresponding position when the system is assembled andthen fixedly connected to the lower layer of the laminated bus barsthrough a stud installed by the system.

It should be noted that, in the above exemplary embodiments, the powermodule may further include typical components or structures, such as achip, a potting glue, a housing and so on, all of which belong to aportion that can be configured by a person skilled in the art accordingto requirements, which is not specifically limited by the presentexemplary embodiment.

Further, embodiments of the present disclosure also provide a. powermodule assembly structure, wherein the power module assembly structuremay include: a substrate; two power elements connected in serialdisposed on the substrate; a first conductive strip and a secondconductive strip. in the embodiment, the two power elements connected inseries are disposed on the substrate. The first conductive strip and thesecond conductive strip are coupled to the two power elementsrespectively. In the embodiment, the first conductive strip and thesecond conductive strip extend from the substrate to a first side of thepower module assembly structure in parallel and two connecting terminalsare formed on the first side. An extending portion exists between thetwo connecting terminals, and the extending portion overlaps with anexternal conductive strip to reduce a parasitic inductance between thetwo connecting terminals.

As for the above power module assembly structure, within the powermodule, the first conductive strip and the second conductive strip arearranged in parallel to achieve counteraction of the current and reducethe parasitic inductance inside the power module. At the fan-out end ofthe power module, the counteraction of the current may also be achievedby overlapping an extending portion and an external conductive strip,which can reduce the parasitic inductance between the fan-out terminalsof the power module. It should be noted that the first conductive stripmay correspond to the above-mentioned first bus bar; the secondconductive strip may correspond to the above-mentioned second bus bar;and the external conductive strip may correspond to the above-mentionedthird bus bar, but the present disclosure does not limit it to this.Through the cooperation of the above two aspects, the parasiticinductance inside the power module can be greatly reduced, therebyeasily and effectively reducing the voltage stress and power loss of thepower electronic semiconductor element, and thereby improving thereliability and safety of the power electronic device.

Other embodiments of the present disclosure will readily occur to thoseskilled in the art upon consideration of the specification and practiceof the disclosure disclosed herein. The present application is intendedto cover any variations, uses, or adaptations of the present disclosurethat follow general principles of the present disclosure and includecommon knowledge or conventional technical means in the art which arenot disclosed herein. The specification and embodiments are consideredas exemplary only, with the true scope and spirit of the presentdisclosure being indicated by the appending claims.

What is claimed is:
 1. A component structure, for connecting a powermodule and an external circuit, wherein the component structurecomprises: a first bus bar, having a first extending portion and a firstbending portion, and the first bending portion extending to a firstplane to form a first connecting terminal; a second bus bar, comprisinga second extending portion, a second bending portion and a rear portionof the second bus bar, wherein the second extending portion and thesecond bending portion are respectively laminated in parallel with thefirst extending portion and the first bending portion, and the rearportion of the second bus bar is extended to a second plane to form asecond connecting terminal; and the external circuit comprising a. thirdbus bar, wherein the third bus bar is settled in parallel with the rearportion of the second bus bar; wherein a portion of the third bus bardisposed opposite to the rear portion of the second bus bar is a frontportion of the third bus bar, and a surface of the rear portion of thesecond bus bar disposed opposite to the front portion of the third busbar is a first surface, and an area. ratio of an overlapping area of therear portion of the second bus bar and the front portion of the thirdbus bar to the first surface is greater than 0.5.
 2. The componentstructure according to claim 1, wherein the rear portion of the secondbus bar is connected with the second bending portion, and both thesecond bending portion and the rear portion of the second bus bar arelocated in the second plane.
 3. The component structure according toclaim 2, wherein one end of the third bus bar is provided with a thirdconnecting terminal, and the third connecting terminal is stacked andconnected with the first connecting terminal; the external circuit isfurther provided a fourth connecting terminal, and the fourth connectingterminal and the second connecting terminal are stacked and connected.4. The component structure according to claim 1, wherein the first busbar further comprises a rear portion of the first bus bar which isconnected with the first bending portion and extended to the first planeto form the first connecting terminal; and an extending direction of therear portion of the first bus bar is opposite to that of the rearportion of the second bus bar.
 5. The component structure according toclaim 4, wherein the third bus bar has a front portion of the third busbar and a rear portion of the third bus bar, the external circuitfurther comprises a fourth bus bar, the four bus bar has a front portionof the fourth bus bar and a rear portion of the fourth bus bar; thefront portion of the third bus bar is settled in parallel with the rearportion of the second bus bar; the front portion of the fourth bus baris settled in parallel with the rear portion of the first bus bar, andthe rear portion of the fourth bus bar is settled in parallel with therear portion of the third bus bar.
 6. The component structure accordingto claim 5, wherein the front portion of the third bus bar is providedwith a third connecting terminal, and the third connecting terminal isconnected with the second connecting terminal; the front portion of thefourth bus bar is provided with a fourth connecting terminal, and thefourth connecting terminal is connected with the first connectingterminal.
 7. The component structure according to claim I, wherein thecomponent structure further comprises a fifth bus bar, the fifth bus barcomprises a front portion of the fifth bus bar and a rear portion of thefifth bus bar, the front portion of the fifth bus bar is laminated inparallel with the first bus bar, and the rear portion of the fifth busbar is extended to a third plane to form a fifth connecting terminal;the external circuit further comprises a fourth bus bar, and the fourthbus bar is settled in paral1el with the rear portion of the fifth busbar.
 8. The component structure according to claim 7, wherein the thirdbus bar has one end provided with a third connecting terminal, and thethird connecting terminal is stacked and connected with the secondconnecting terminal; the fourth bus bar has one end provided with afourth connecting terminal, and the fourth connecting terminal isstacked and connected with the fifth connecting terminal; the externalcircuit is further provided with a sixth connecting terminal, and thesixth connecting terminal is stacked and connected with the firstconnecting terminal.
 9. The component structure according to claim 7,wherein the first bus bar is located between the second extendingportion and the second bending portion of the second bus bar and thefront portion of the fifth bus bar; or the second extending portion andthe second bending portion of the second bus bar is arranged in parallelwith the front portion of the fifth bus bar.
 10. A component structure,for connecting a power module and an external circuit, wherein thecomponent structure comprises: a first bus bar, having a first extendingportion and a first bending portion, and the first bending portionextending to a first plane to form a first connecting terminal; a secondbus bar, comprising a second extending portion, a second bending portionand a rear portion of the second bus bar, wherein the second extendingportion and the second bending portion are respectively laminated inparallel with the first extending portion and the first bending portion,and the rear portion of the second bus bar is extended to a second planeto form a second connecting terminal; and the external circuitcomprising a third bus bar, wherein the third bus bar is settled inparallel with the rear portion of the second bus bar; wherein the rearportion of the second bus bar is connected with the second bendingportion, and both the second bending portion and the rear portion of thesecond bus bar are located in the second plane.
 11. The componentstructure according to claim 10, wherein a portion of the third bus bardisposed opposite to the rear portion of the second bus bar is a frontportion of the third bus bar, and a surface of the rear portion of thesecond bus bar disposed opposite to the front portion of the third busbar is a first surface, and an area ratio of an overlapping area of therear portion of the second bus bar and the front portion of the thirdbus bar to the first surface is greater than 0.5.
 12. The componentstructure according to claim 10, wherein one end of the third bus bar isprovided with a third connecting terminal, and the third connectingterminal is stacked and connected with the first connecting terminal;the external circuit is further provided a fourth connecting terminal,and the fourth connecting terminal and the second connecting terminalare stacked and connected.
 13. The component structure according toclaim 10, wherein a current conducting direction of the first bus bar isopposite to that of the front portion of the second bus bar, and acurrent conducting direction of the rear portion of the second bus baris opposite to that of the third bus bar.
 14. The component structureaccording to claim 10, wherein both the first connecting terminal andthe second connecting terminal are plug-in terminals.
 15. A componentstructure, for connecting a power module and an external circuit,wherein the component structure comprises: a first bus bar, having oneend extending to a first plane to form a first connecting terminal; asecond bus bar, comprising a front portion of the second bus bar and arear portion of the second bus bar, wherein the front portion of thesecond bus bar is laminated in parallel with the first bus bar, and therear portion of the second bus bar is extended to a second plane to forma second connecting terminal; a fifth bus bar, comprising a frontportion of the fifth bus bar and a rear portion of the fifth bus bar,wherein the front portion of the fifth bus bar is laminated in parallelwith the first bus bar, and the rear portion of the fifth bus bar isextended to a third plane to form a fifth connecting terminal; and theexternal circuit comprising a third bus bar and a fourth bus bar,wherein the third bus bar is settled in parallel with the rear portionof the second bus bar; and the fourth bus bar is settled in parallelwith the rear portion of the fifth bus bar.
 16. The component structureaccording to claim 15, wherein a portion of the third bus bar disposedopposite to the rear portion of the second bus bar is a front portion ofthe third bus bar, and a surface of the rear portion of the second busbar disposed opposite to the front portion of the third bus bar is afirst surface, and an area ratio of an overlapping area of the rearportion of the second bus bar and the front portion of the third bus barto the first surface is greater than 0.5.
 17. The component structureaccording to claim
 15. wherein a portion of the fourth bus bar disposedopposite to the rear portion of the fifth bus bar is a front portion ofthe fourth bus bar, and a surface of the rear portion of the fifth busbar disposed opposite to the front portion of the fourth bus bar is asecond surface, and an area ratio of an overlapping area of the rearportion of the fifth bus bar and the front portion of the fourth bus barto the second surface is greater than 0.5.
 18. The component structureaccording to claim 15, wherein the first connecting terminal, he secondconnecting terminal and the third connecting terminal are plug-interminals.
 19. The component structure according to claim 15, whereinthe third bus bar has one end provided with a third connecting terminal,and the third connecting terminal is stacked and connected with thesecond connecting terminal; the fourth bus bar has one end provided witha fourth connecting terminal, and the fourth connecting terminal isstacked and connected with the fifth connecting terminal; the externalcircuit is further provided with a sixth connecting terminal, and thesixth connecting terminal is stacked and connected with the firstconnecting terminal.
 20. The component structure according to claim 15,wherein the first bus bar is located between the front portion of thesecond bus bar and the front portion of the fifth bus bar; or the frontportion of the second bus bar is arranged in parallel with the frontportion of the fifth bus bar.